Pierce nut

ABSTRACT

A pierce nut having an attachment member extending axially from one end of a nut body. The attachment member is adopted to pierce a sheet member and then secure the nut to the sheet member. The attachment member is substantially square in transverse section and has a groove formed in its sides so that it can engage and grip the sheet member. The sides of the attachment member taper outwardly from its outer edge forming a cutting edge for piercing the sheet member.

United States Patent [72] Inventor Horace D. Holmes, Birmingham, Mich.[211 Appl. No. 832,611

[22] Filed June 12, 1969 [45] Patented Aug. 17, 1971 [73] Assignee MascoCorporation, Taylor, Mich.

[541 LOCK NUT ASSEMBLY AND METHOD OF MAKING THE SAME 6 Claims, 16Drawing Figs.

52 vs. C] 151 2 R; 29/5l7;l51/21C 51] 1111. C1 ..F16b 39 02 50FieldofSearch 151/2, 2 A, 21 c, 22, 30; 85/7, 46; 29/517 ReferencesCited UNITED STATES PATENTS 78,899 6/1868 Smith 151/21 C 930,450 8/1909Zinow 151/2 A 3,163,196 12/1964 I-Ianneman 85/46 3,249,142 5/ 1 966Phipard 85/46 3,258,797 7/ 1 966 Budd 85/46 3,385,340 5/1968 Evans151/22 3,421,562 1/1969 Orloff et a1 151/2 3 ,464,472 9/1969 Reynolds151/2 3,479,714 11/1969 Allsop 151/21 C FOREIGN PATENTS 514,470 12/1930Germany 151/2 A Primary Examiner-Marion Parsons, Jr.Attorneys-Whittemore, Hulbert & Belknap ABSTRACT: A lock nut assemblyand method of making the same in which a non-circular bolt shank orother fastener body is provided with rolled threads of uniform deptharound its entire circumference and a standard nut having a circularthreaded aperture is threaded onto the bolt and then deformed radiallyinwardly to effect complete engagement of the threads of the nut withthe threads of the bolt around the entire circumference of the bolt. Thenut may be removed from the bolt with the use of a power tool and thenreapplied to the bolt in the same manner.

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sumaurz INVENTOR. HORACE D. HOLMES BY 95AM, ad-4) W ATTORNEYS LOCK NUTASSEMBLY AND METHOD OF MAKING THE SAME Lock nut systems in commercialuse require the provision of a specially made nut or bolt or both, or aseparate locking element. The present invention is directed to theprovision of a lock nut assembly consisting of a bolt and a standardnut, without the use of a lock washer or other similar locking element,which is capable of being disassembled and reassembled many timeswithout any decrease in the efficiency or performance of the assembly.According to the invention, a bolt or other fastening member ofnon-circular cross section is provided with standard threads of uniformdepth around its entire circumference, preferably by rolling threads onthe bolt shank, and a standard nut having a circular threaded apertureis then threaded onto the bolt with the threads of the nut in fullengagement with the threads of the bolt across the larger crosssectional dimensions of the bolt and in partial engagement across thesmaller cross sectional dimensions of the bolt. After the nut is rundown to the required torque the nut is squeezed or deformed radiallyinwardly to cause the threads thereof to flow into full engagement withthe threads of the bolt around the entire circumference of the bolt,thus greatly increasing the removal torque of the assembly. With thisconstruction it is impossible for the nut to become loosened due tovibration and other stresses in the assembly in which the nut and boltare used. The nut can be removed from the bolt with the use of a powerwrench which returns the nut aperture to its original circularconfiguration, and the nut can be reapplied to the bolt by the samemethod described above. With the lock nut assembly and method describedherein there is no galling or permanent distortion of the threads ofeither the bolt or the nut, thus insuring that the parts may bedisassembled and reassembled as often as may be required.

In the drawings:

FIG. I is an elevational view of a bolt blank having a noncircular shanksuitable for use in this invention;

FIG. 2 is an end elevational view of the bolt blank of FIG. 1.illustrating a bolt having a shank which is elliptical in cross section:

FIG. 3 illustrates a modified form of bolt in which the shank is squarein cross section with the corners thereof provided with a suitableradius;

FIG. 4 is a schematic illustration of a portion of a thread rollingapparatus which may be employed to roll threads of uniform depth on anon-circular bolt or other fastening element;

FIG. 5 is a side elevational view of the thread rolling dies shown inFIG. 4;

FIG. 6 is a fragmentary elevational view of a bolt provided with threadsaccording to this invention;

FIG. 7 is a sectional view taken on line 7-7 of FIG. 6;

FIG. 8 is a sectional view similar to FIG. 7 of a bolt having a squarecross section;

FIG. 9 is an end elevational view showing a standard nut threaded ontoan elliptical bolt;

FIG. 10 is a sectional view taken on line III-10 of FIG. 9, showing theengagement of the threads prior to squeezing of the nut onto the bolt;

FIG. 11 is a view similar to FIG. 9 showing the assembly after the nuthas been deformed to provide full engagement between the threads of thenut and the bolt;

FIG. 12 is a sectional view taken on line 12-- 12 of FIG. 11;

FIG. 13 is a fragmentary sectional view of a power tool which may beused to apply the nut to the bolt;

FIG. 14 is an enlarged fragmentary sectional view of a" portion ofthecollet used in the apparatus of FIG. 13;

FIG. [5 is an end elevational view ofthe collet; and

FIG. 16 is an elevational view illustrating the lock nut assembly beforeand after the application of pressure to deform the nut into engagementwith the bolt.

A male fastening element. such as a bolt, is formed from a bolt blankillustrated in FIG. 1. The blank consists of a hexagonal or other shapedhead 10 and a shank portion 12 which is non-circular and preferably ofelliptical cross section as shown in FIG. 2. The blank may be made bycold heading or any other suitable manner. The blank may also have ashank 14 of square cross section as shown in FIG. 3, and in fact theshank may be provided with any even number of sides, with the ellipticalconfiguration shown in FIG. 2 being considered as a two-sided blank inthe sense that the radial extent of two diametrically opposed portionsis less than the largest diameter of the shank.

It has been found that threads of uniform diameter throughout thecircumferential extent of thebolt may be formed thereon by rolling thethreads in a conventional 3-die thread rolling apparatus which isillustrated schematically in FIGS. 4 and 5. In a thread rolling machineof this type the elliptical bolt shank 12 will not rotate on its axis,but the axis thereof will describe a path which will roll threads ofuniform depth entirely around the bolt. This result can be achieved witha blank having any even number of sides. The threads rolled on the blankby the thread rolling dies 16 will be standard threads in that therelationships between the root diameter, the pitch diameter, and themajor diameter will be the same as would be obtained if the same dieswere used to roll threads on a circular blank. The threads may be formedin any other manner if desired.

FIG. 6 illustrates the elliptical shank portion 12 of the bolt after thethreads 20 havebeen rolled thereon. In FIG. 7

the major diameter, the pitch diameter, and the root diameter are,respectively, indicated by the reference characters 22, 24 and 26.Across the largest cross sectional dimension of the threaded shank thesediameters are the same as those of conventional threads for a circularbolt of given size, and across'the minor axis of the elliptical shanksuch dimensions are reduced by a few thousandths of an inch, for example0.005 inch or more, although the depth of the thread remainssubstantially uniform around the entire circumference of the bolt. Inthe case of a square shank shown in FIG. 8, or a shank having any othereven number of sides, the dimensions across the flats are a fewthousandths of an inch less than across the corners. but the threads areof substantially uniform depth throughout.

A nut 30, which may be a standard hexagonal nut having a circularthreaded aperture, the threads of which are the same as those on thebolt, is adapted to be threaded onto the bolt as shown in FIG. 9. InFIG. 9 the reference character 32 indicates the root diameter of thethreads formed in the nut 30, and from FIG. 10 it will be seen that whenthe nut 30 is threaded onto the bolt 12 to engage a part 34 adapted tobe secured by the nut and bolt assembly, the threads of the nut and boltacross the largest dimension of the bolt are in full engagement whilethe threads across the smallest dimension or minor axis of the bolt arein partial engagement only, due to the few thousandths of an inchdifferential between the major and minor axes of the bolt.

FIGS. 11 and 12 illustrate the assembly after the nut has been deformedradially inwardly to cause complete engagement of the threads of the nutwith the tln eads of the bolt around the entire periphery of the bolt.The squeezing of the nut to effect this engagement of the threads may beaccomplished in any number of ways, one of which is illustrated in FIGS.13-15. FIG. 13 illustrates a power tool of the gun type which mayinclude a handle portion 40 and a cylindrical portion 42 defining acylinder 44 containing a piston 46 rcciprocable therein and mounted on-adrive shaft 48 which at its left-hand end is-adapted to be coupled to asuitable power source supplied through the conduit 50 connected to thehandle portion 40 so that the shaft 48 may be rotated when desired. Theouter end 52 of the shaft is secured to the inner end 54 of a splitcollet 56. The collet 56 has a hexagonal socket 58 opening from itsouter end and a communicating smaller diameter bore 60. A series ofslots 62 are provided throughout the major portion of the length of thecollet to define individual spring segments 64. Each of the slots 62 ispreferably disposed at one of the corners of the hexagonal socket 58 inthe collet. A sleeve 66 is slidably mounted within the cylinder 44 ofthe power tool and has a tapered portion 68 at its outer end engageablewith a correspondingly tapered surface 70 on the collet 56.

The power tool shown in FIG. 13 may be utilized to run the nut down onthe bolt to the required torque by rotation of the shaft 48 with the nutconfined within the socket 58 1 in the collet 56. Power wrenches of thistype are well known, and the device illustrated in FIG. 13 may beconsidered merely illustrative of one type of power tool that may besuitable for this purpose. After the nut is tightened to the requiredextent, fluid pressure may be supplied through the conduit 50 into theleft-hand end of cylinder 44 against piston 46 to force the latter andthe sleeve 66 outwardly to contract the segments 64 of the colletagainst the side surfaces of the nut. Each face of the socket 58 in thecollet may be provided with a raised pad 72 of square or other shape sothat the collapsing of the collet will effect the application ofpressure of metal deforming intensity against the sides of the nut todeform the same radially inwardly to obtain full engagement of thethreads of the nut with the threads of the bolt throughout thecircumferential extent of the bolt. It will be apparent that upon theapplication of pressure in the manner described, those of the segments64 which engage the portions of the bolt lying on or closely adjacentits major axis will not be deflected to as great an extent as theremaining segments. or in any event will not cause the metal ofthe nutin the area of the fully engaged threads to flow. but rather will aid ineffecting a flow of the metal of the nut toward the areas thereofopposite the minor dimensions of the bolt, thereby to effect fullengagement of the threads entirely around the bolt.

FIG. 16 illustrates an assembly of parts adapted to utilize two or moreof the lock nut assemblies of this invention and in the left-handportion shows a bolt 12 having a nut 30 threaded thereon prior todeformation of the nut, and in the right-hand portion illustrates a nut30 after the same has been deformed into full engagement with the bolt.The lock nut assembly described herein may be can'ied out by separatetools to tighten the nut to obtain the required torque and to effect thedistortion necessary to lock the nut onto the bolt, rather than by asingle tool as disclosed herein. In either event, the lock nut assemblyis well adapted for use in the mass production assembly of parts, or toindividual application as may be required. It is also contemplated thatthe nut initially may be run down finger tight and the final clampingforce applied during the operation of squeezing the nut to provide fullengagement of the threads.

A bolt shank having three sides or any odd number of sides may also beutilized in practising the invention, although the forming of thethreads thereon may be carried out by other appropriate thread rollingor other conventional techniques.

The lock nut of this invention has the advantage of utilizing aconventional standard nut and a bolt which may be produced veryinexpensively by conventional mass production techniques tosubstantially reduce the cost of the parts as compared with commerciallyavailable lock nut constructions, and provides an assembly having veryhigh removal torque to prevent any possibility of accidental removal orloosening of the nut.

- What I claim as my invention is:

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nut assembly which comprises: providing 'an externally threaded fastenerbody of non-circular cross section which is only slightly out of roundand smoothly and gradually curved around its entire circumference andhaving uniform threads of substantially uniform depth around the entirecircumference and throughout the entire threaded length thereof.threading a standard nut having a circular threaded aperture onto saidbody to fully engage the threads at spaced points around thecircumference of said body andto only partially engage the remainder ofthe threads, and then applying pressure of metal deforming intensity tothe sides of the nut sufficient to cause substantially completeengagement of the threads of the nut with the body around the entirecircumference of the body.

2. The method of making a removable and reusable lock nut assembly whichcomprises: forming a bolt blank having a shank portion of non-circularcross section which is only slightly out of round and smoothly andgradually curved around its entire circumference, and forming uniformthreads on said bolt shank to a uniform depth around the entirecircumference and along the entire threaded length of said shank,threading a standard nut having a circular threaded aperture onto saidbolt to fully engage the threads at spaced points around thecircumference of the bolt and to only partially engage the remainder ofthe threads, and then applying pressure of metal deforming intensity tothe sides of the nut sufficient to cause substantially completeengagement of the threads of the nut with the bolt around the entirecircumference ofthe bolt.

3. The method of making a removable and reusable lock nut assembly whichcomprises: forming a bolt blank having a shank portion of non-circularcross section which is only slightly out of round and smoothly andgradually curved around its entire circumference and which issymmetrical about at least two perpendicular planes, rolling threads onsaid bolt shank to a uniform depth around the entire circumference andalong the entire length of the threaded portion of said shank, providinga standard nut having a circular threaded aperture, threading said nutonto said bolt to fully engage the threads at the major diameters acrossthe boltand to only partially engage the threads across the minordiameters thereof, and then applying pressure of metal deformingintensity to the sides of the nut sufficient to cause substantiallycomplete engagement of the threads of the nut with the threads of thebolt around the entire circumference of the bolt.

4. A removable and reusable lock nut assembly comprising the combinationof a bolt having a shank of non-circular cross section which is onlyslightly out of round and smoothly and gradually curved around itsentire circumference and provided with standard threads of uniform deptharound its entire circumference and along its entire threaded length.and a standard nut having an initially circular threaded aperturethreaded onto said bolt and deformed radially inwardly to causesubstantially complete engagement of the threads of the nut with thethreads ol'the bolt around the entire circumference of the bolt.

6. An assembly according-to claim 5 wherein said.nut is deformed at atleast two circumferentially spaced points.

1. Pierce nut comprising a tapped nut body and an integral tappedattachment member projecting axially from one end face of said nut bodyand having a free end face extending transversely of the axis of saidnut and lateral surfaces extending between said free end face and saidone end face of said nut body, said attachment member serving as a punchto form an opening in a metal plate to which said nut is to be securedwhen forcing the nut into said plate with said free end face inengagement with one side of said plate, said attachment member having inat least some of said lateral surfaces an undercut recess adapted to beengaged by an edge portion of the opening formed in the metal plate,wherein the improvement comprises the combination of the followingfeatures: a. said attachment member in all planes normal to the axis ofsaid nut being substantially square with straight sides; b. the cornersof said attachment member joining adjacent straight sides being roundedoff in the plane normal to the axis of said nut; c. all of said lateralsurfaces sides of said attachment member having the undercut recesstherein forming a continuous recess about said attachment member; d.said attachment member being centrally disposed on said nut body whichin a plane normal to the axis of said nut extends laterally outwardly onall sides from the lateral surfaces of said attachment member so thatsaid one end face of said nut body forms an unbroken contact surfacespaced from and extending circumferentially around said attachmentmember; e. said nut body has a depression running circumferentiallyaround said one end face and said depression adjoins said attachmentmember and said undercut recess and has a configuration in a planenormal to the axis of said nut closely similar to the outer contour ofthe attaChment member in a plane parallel thereto having foursubstantially straight sides and with rounded corners between adjacentsides; f. the radially outer surface of said depression sloping inwardlyrelative to the axis of the nut body from said one end face thereof to atransverse bottom surface which joins the side surface of said undercutrecess; g. said lateral surfaces of said attachment member taperingoutwardly from said free end surface toward said nut body to a smoothrounded off portion and then tapering inwardly to define in part saidundercut recess, and said outwardly tapering surfaces amounting to about10 -60 percent of the total axial dimension of said attachment member:and h. said tapering surfaces merging smoothly with the undercut recessin said side surface.
 2. Pierce nut, as set forth in claim 1,characterized therein that the angle of the tapering portions of saidlateral surfaces being between one degree and 20* relative to axis ofsaid nut.